On Monday we mentioned that the MTA has started offering free e-books underground as part of its Subway Reads program, but they weren’t the first to make books an integral part of the public transit experience. London’s Books on the Underground was first, but then came a more interesting development in Australia: book ninjas. Books on the Rails is a gonzo experiment started by two Melbourne residents who began releasing free books – actual, paper books – into the wilds of the city’s tram system. About 300 books are currently in circulation in what’s possibly the world’s most open lending library.